Goodwill and Other Intangible Assets - Intangible Assets (Details) - USD ($) $ in Millions	6 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Sep. 30, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 615		$ 617
Accumulated Amortization	(174)		(157)
Net	441		460
Amortization of intangibles	20	$ 24
Patented technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	20		21
Accumulated Amortization	(14)		(14)
Net	6		7
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	514		509
Accumulated Amortization	(117)		(101)
Net	397		408
Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	53		58
Accumulated Amortization	(31)		(30)
Net	22		28
Miscellaneous
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	28		29
Accumulated Amortization	(12)		(12)
Net	$ 16		$ 17

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount before accumulated amortization of intangible assets, excluding goodwill.

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Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

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